1. Field of the Invention
The present invention relates to a fuel injection valve of a type in which fuel is injected by opening and closing a needle valve.
2. Description of the Related Art
FIG. 7 is a sectional view showing a conventional fuel injection valve. In the drawing, reference numeral 11 designates a coil; 12, an armature; 13, a core; 14, a needle valve; 15, a valve seat; and 16, a spring.
Its operation will next be explained. When current is applied to the coil 11, the armature 12 is attracted toward the side of the core 13, the needle valve 14 provided integrally with the armature 12 is separated from the valve seat 15, and fuel is injected from a gap between the valve seat 15 and the needle valve 14. When current application to the coil 11 is cut off, the needle valve 14 is pressed to the side of the valve seat 15 by the spring 16, and the needle valve 14 comes into contact with the valve seat 15. The amount of fuel injection is controlled by opening and closing of this needle valve 14.
Since the conventional fuel injection valve is constructed as described above, there have been such problems that a shock is generated when the needle valve comes to be seated on the valve seat, and this results in an operation sound of the fuel injection valve, and becomes a factor of deterioration in durability since the needle valve and the valve seat are worn down.
Incidentally, it is needless to say that it is appropriate that the shock at the time when the needle valve comes to be seated on the valve seat is as low as possible.
The present invention has been made to solve the problems as set forth above, and has an object to provide a fuel injection valve in which a shock at the time of seating of a needle valve is made low so that an operation sound is lowered, and durability of a valve seat and a needle valve is raised.
According to the present invention, a fuel injection valve includes a hollow valve body, a valve seat provided at one end of the valve body and having an injection hole, and a needle valve moving in the valve body and coming in contact with and separating from the valve seat to open and close the injection hole, in which a shoulder portion is provided at the needle valve, and a ring is provided at a lower surface side of the shoulder portion, so that a portion for confining fuel is formed between a lower end surface of the shoulder portion and an upper end surface of the ring.
Thus, the operation sound is lowered, the durability can be improved, and the adjustment of fluid damping effect becomes possible.